UNIVERSITY PARK, Pa., July 20 (UPI) — Our nurturing of other species — cats, dogs and the like — may have played a crucial role in our own human evolution, a U.S. scientist says.

Pat Shipman of Pennsylvania State University argues man’s relationship with animals goes well beyond simple affection, and that “the animal connection” played an important and beneficial role in 2.6 million years of evolution, a university release said Tuesday.

“Establishing an intimate connection to other animals is unique and universal to our species,” Shipman, a biological anthropologist, said.

“Every mouthful you feed to another species is one that your own children do not eat. On the face of it, caring for another species is maladaptive, so why do we humans do this?”

Shipman argues the connection resulted from the invention of stone tools 2.6 million years ago.